FONTANA (CBSLA.com) — An apparent shooting threat made on social media against a Fontana high school has been determined to not be serious, authorities said Monday.

KNX 1070’s Bob Brill reports police made the conclusion following a pair of investigations involving two apparent Summit High School students.

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Officers received a report at around 8:21 p.m. Sunday night about a post on Instagram showing an unidentified subject claiming to be a student at Summit High School hold multiple guns, according to Fontana Police spokeswoman Martha Guzman-Hurtado.

The post included a caption with the question, “Guess what I’m doing tomorrow?” Guzman-Hurtado said.

After officers responded to the student’s residence, investigators concluded that the unidentified teen had plans with his family to go to the shooting range, according to Guzman-Hurtado.

Police say the parents were “completely cooperative” and voluntarily surrendered six legally owned handguns and rifles to police for “safekeeping.”

It was not immediately clear when the firearms would be returned.

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Police say a second investigation was launched after a Twitter user replied to the original Instagram post with a tweet that read,”I’m the one shooting up the school.”

Investigators later determined that the second subject – who was unidentified – “had no way or means to follow through with the vague threat”.

“Law enforcement is satisfied there is no credible threat and no danger to our students or staff, and they are our number one priority,” said Ollie Wong of the Fontana School District.

Classes resumed as usual Monday, while a “larger police presence” was seen on campus.

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The student was not arrested and has since apologized, even referring to himself as an “idiot” on social media.